Ink is a liquid substance used for writing or drawing, primarily composed of pigments or dyes suspended in a solvent. It can be used with various writing instruments such as pens, markers, or brushes, and is available in a wide range of colors and consistencies, from regular ink to water-resistant ink or ink with special effects. Ink is essential in the workplace, education, and creative activities, offering a versatile and durable means of expression and written communication.